Dual-resonator Lamb wave strain sensor with temperature compensation and enhanced sensitivity.

In this letter, we demonstrate a high-temperature dual-resonator Lamb wave tensile strain sensor which can achieve temperature compensation in a wide temperature range and has high strain sensitivities. This sensor consists of two identical AlN-on-SOI Lamb wave resonators (LWRs) adhered on a uniaxial tensile plate, with the wave propagating directions in the two LWRs parallel and perpendicular to the tensile axis, respectively. The most obvious higher-order Lamb wave modes, i.e., the A₄, S₄, and S₅ modes, in the “parallel” LWR present high strain sensitivities of 0.229 ppm/με (196 Hz/με), 0.480 ppm/με (431 Hz/με), and 0.222 ppm/με (205 Hz/με) all with minus signs, whereas in the “perpendicular” LWR, they demonstrate smaller strain sensitivities all with plus signs. The S₄ modes in the two LWRs have almost the same temperature coefficients. Based on the experimental results, a generally applicable beat frequency method with these two LWRs is proposed to realize temperature compensation as well as the high-sensitivity strain measurement. [ABSTRACT FROM AUTHOR]